Process of making cutting blowpipe tips



Jan- 28, 1936. l. CAMPBELL, .1R

PROCESS 0F MAKING CUTTING BLOWPIPE TIPS Filed Feb. l5.' 1931 Patented Jan. 28, 1936 PROCESS .0F MAKING CUTTING BLOWPIPE TIPS Lorn Campbell, Jr., Lakewood, Ohio Application'rebmary 13, 1931, serial No. 515,524

2 Claims.

l This invention relates to a process of making cutting tips for blowpipes, and has for its general object to produce a tip which will be particularly eilicient in operation and especially useful in operating with fuel gas under low pressure (from four to six ounces per square inch).

As is well known in the art of cutting metal with blowpipes, it is necessary that the passages for the preheating mixture shall converge toward the operating end of the tip in such manner that the preheating flames shall impingeupon avsmall area only of the metal, in order to insure quick preheating ofthe metal and to enable the cutting operation to be initiated with correspondin quickness or rapidity.

It has been customary heretofore, in fabricating cutting tips, to provide the central oxygen bore and the surrounding bores for the preheating mixture by drilling larger passages from the upper end of the tip body to the upper end of the tapered or frusta-conical operating` e'nd of the body and then to drill smaller passages from the operating end of the tip body to intersect the lower ends of the-corresponding largenp'assages. It has been found very diicult to obtain accurate ,registration of the junctions of the'smaller and larger passages; and this lack of accurate registration at the junctions will result in irregularities at the junctions with consequent irregularities in the character of the preheating ames. If one of them fails to register with the others, the metal will be preheated unequally and inefciently, with a resultant lackof efliciency in the operation of the tip and a corresponding increase in the consumption of tank oxygen.

In order to overcome these objections, I have constructed tips for cutting blowpipes in the manner described hereinafter and illustrated in the accompanying drawing, wherein Fig. 1 represents a side elevation of a tip for a cutting blowpipe; Fig. 2 a bottom plan view and Fig. 3

a top plan View of the said tip; Fig. 4 a central y longitudinal sectional view through the blank from which the said tip is made, the said blank ing the nished tip with the wires o r mandrels removed. l

In the production of a tip made in accordance sible to use the purest copper and to make the vlength of the blank and parallel with the central with my invention, I prefer to employ a blank of pure 'electrolytic copper, which possesses great heat radiating properties and which, because of its high conductivity, carries the reflected .heat of the intense flame (having a temperature of 6300 5 F.) away from the operating ends of the tips and dissipates and radiates it into the air, thereby prolonging the lives of the tips. The purer the copper employed, the greater its conductivity; but, incidentally, the more diicult is the machin- L ing, because such pure copper is very herd on machine tools and very difficult to work, because of its tenacity. 1

By my process of fabricating the tips, it is posbores continuous and Without irregularities throughout their entire length, whichirregularities produce the objectionable results referred to hereinbefore.

Referring to the drawing, l denotes a cylindrical blank of proper diameter and length for a blowpipe tip, the blank being shown'as providedk at its upper end with a cylindrical enlargement 2 by means of which it may be secured, as by a shouldered nut, to the front or lower end of the 2: blowpipe head. 'Ihis blank is provided with a central bore 3 for cutting oxygen, the said bore being of uniform diameter throughout the length of the blank and with smaller bores 4 grouped about the central bore'and extending the full 'l-i bore and with each other and also being ofthe same diameter throughout their respective lengths. At their upper ends the bores 4 are shown as merging with an annular recess 5, such I? 'l as is commonly provided for the distribution to said bores of the preheating mixture from the appropriate passage or passages in the head. Inserted in the bores 3 and 4 are mandrels 6 and 1, the said mandrels being of the diameter desired 1" for lthe delivery or operative ends of the bores within which they are respectively inserted, it being noted that the mandrel 6 is o f somewhat greater cross sectional area than the mandrels 5.

The mandrels having been thus inserted, the lower or operative end of the tip is shaped, as by swaging, so as to give it the truste-conical form indicated at 8, the lower oroperative ends' of the bores 3 and 4 being thereby reduced in cross sectional area to an extent determined by thc engagement o'f the Wallsof the bores with the mandrels.

As will be evident from an inspection of Figs. 6 and 7, the reduced lower or operative ends 3 and 4 of the bores 3' and 4 respectively merge sznooih- 55 with former practices, and the preheating llames ly and uninterruptedly with the main or larger portions of said. bores. Heretofora the junctions of the Vreduced and smaller portions of these bores have produced irregularities .in Ythe bores at such junctions, and these irregularities have in turn resulted in the production of ilames ofunequal lengtlriissuing' from the preheating jets, with the consequent inefciencyin the preheating operation pointed out hereinbefore. @i

A blowpipe tip constructed in accorwance with my invention will produce amore concentrated and intense preheating name than is ordinarily obtainable from tips constructed in accordance the preheating p/assages, the combustion of the acetylene being completed by'oxygen ladmitted to the deoxidized zone within the preheating flames. In the case of a harsh or blcwyame, the molten metal is agitated and atmospheric oxygen is conveyed into the zone which should be enclosed by theburning preheating jets at their contact; with the metal and which zone should be deoxidized by the chemical reaction of the ame. Where the atmospheric oxygen breaks into this zone, it not only results in ineiciency in theV cutting operation itself, `but necessitates the use of more tank oxygen for the productln of thepreheating mixture. By producing a bloglpipe tip4 having passages free from irregularities, I amenabled to overcome the objections noted hereinbefore; and, as pointed out, a tip having such smooth and unobstructed passages is particularly eiective -for the use of lowpressure combustible gas. Furthermore, by'siaging the operating end of the tip, the metal iscondensed and compacted and its conductivity is thereby increased, enabling the intense heat to which this end of the tip is subjected to beconduct'ed quickly to the body of the tip land'to be radiated therefrom, with a corresponding increase in the life of the tip. Y i Y Having thus described my invention, what I claim is: Y

1. The process of ri'laking' Aa unitary blowpipe tip having a central here for cutting oxygen and a plurality of borejs' for preheating mixture grouped about suchgicentral bore, said process consisting in providin'g'a blank of ductile metal;

for cutting oxygen extending longitudinally therethrough and withaplurality of boresjrfor prelieating Ymixturei extending longitudinally therethrough and grouped about the Ycentral bore and Ysubstantially parallel therewith and communicating each at one end with recess; inserting into said bore cylindrical uandrels of smaller diameters than the diameters of said bores; and subjecting the Wend of said blankwhich is opposite the one provided 4with the annular recess to pressure in siichmanner thatY the `said end is given a substantially misto-conical shape, the delivery portionsjof all of said bores are brought into engagement with the corresponding portions or said mandrels therein, and

the delivery end pojrtions of the bores for preheating mixture arereduced in diameter and are inclined toward thel'reduced delivery end of the forming in one end of said blank an annulai` recess; providing said 'blank with a central bore-for cutting oxygen of substantially uniferm diana-eter throughout its length and extending longitudinally therethrough and with a. plurality olf bores for preheating mixture extending lngitudinally therethrough and grouped about the central bore and substantially parallel therewith and communicating each at one vend r with-said recess and each .being -of substantialy uniform diameter throughout'its length; inserting into said bore thediameters of said bores: and-:subjecting the endY of said blank 4which is bpposite'the one provided with the annular recess to pressure in' such cylindrical mandreis of smaller diameters than manner that the said end is given a substantially f" vfrusta-conical shape, the delivery portions of all of said bores are brought into engagement with the corresponding portions of said mandi-els therein, and the delivery end portioisof the bores for preheating mixture are reduced in diameterv and are inclined toward the v.reduced delivery end of the central bore and the delivery end portion of each bore for preheating mixture merges smoothly with the enlarged portionl of such bore .whichfis remote from the delivery end of the tip. 

